It is common to use a wood stove as a source of home heat, and extensive efforts have been made to improve the heat output of wood stoves and to reduce the amount of pollution generated through use of such stoves. These goals are not inconsistent, in that a substantial portion of the pollutants generated by a wood stove are combustible, and therefore by ensuring more complete combustion the quantity of pollutants is reduced and additional heat is released.
U.S. Pat. No. 4,319,556 (Schwartz et al) discloses a wood burning stove having four chambers through which gas passes successively from an air inlet of the stove to a flue outlet. Only the second and third of these chambers are combustion chambers, the fourth chamber being a heat exchange chamber.
U.S. Pat. No. 4,432,335 (Kilham) discloses a wood burning stove having ducts for introducing air into the combustion chamber in a downwards direction.